| || || |
|Parameter ||Spectral Window (nm) ||Layer ||Quantity (column) ||Retrieval Algorithm ||Retrieval Algorithm Reference |
|O3 ||325 335 ||troposphere, stratosphere ||total ||operationalWFM-DOASTOSOMISDOAS ||Spurr 2000 Weber et al. 2005 Eskes et al. 2005 Van Roozendael et al. 2006 |
|NO2 ||425-450 ||troposphere, stratosphere ||total, tropospheric ||operational DOAS SDOAS ||Spurr 2000 Richter et al. 2005 Van Roozendael et al. 2006 |
|BrO ||335-347(55) ||troposphere, stratosphere ||total ||DOAS || |
|SO2 ||315-327 ||troposphere ||total ||DOAS || |
|HCHO ||335-347(55) ||troposphere ||total ||DOAS || |
|OClO ||365-389 ||stratosphere ||total ||DOAS || |
|H2O ||688-700 ||troposphere ||total ||AMC-DOAS ||No l et al. 2004 |
|CO ||2321(24)-2335 ||troposphere ||total ||WFM-DOAS IMLMIMAP ||de Beek et al. 2006 de Laat et al. 2006 Frankenberg et al. 2005b |
|CH4 ||1627(30)-1671 ||troposphere ||total ||WFM-DOAS IMLMIMAP ||de Beek et al. 2006 Gloudemans et al. 2005 Frankenberg et al. 2005a |
|CO2 ||1558(63)-1594(85) ||troposphere ||total ||WFM-DOAS IMLMIMAP ||de Beek et al. 2006 Houweling et al. 2005 Frankenberg et al. 2005a |
Table 5-1: Atmospheric geophysical parameters and retrieval algorithms – nadir trace gases.
5.3 Cloud and Aerosol Parameter Retrieval
The primary scientific objective of SCIAMACHY is the measurement of atmospheric trace gases in both the troposphere and stratosphere. However, clouds residing in the troposphere do interfere with the retrievals from SCIAMACHY measurements mainly by the shielding and albedo effects. Similarly, tropospheric and/or stratospheric aerosol interferes with the trace gas retrieval, as it alters the light path. Therefore, there is a clear need for cloud and aerosol information. In addition, cloud information from SCIAMACHY will also provide relevant data for cloud research.
In the UV, VIS and NIR spectral regions the solar radiation is strongly scattered by clouds and aerosol, thereby modifying the Earth reflectance spectrum. The presence of clouds and aerosol and their properties can therefore be determined by analysing the top-of-atmosphere reflection function R. It is defined as (equ. 5-6)
where is the cosine of the solar zenith angle, is the solar irradiance and is the scattered and reflected light in the direction towards the satellite sensor.
Prerequisites for high quality information about aerosol and clouds are high spatial resolution and high calibration accuracy of the reflectance measurements. Typical reflectance spectra for various cloud and surface conditions are shown in fig. 5-7. Various algorithms are required to determine cloud and aerosol properties from SCIAMACHY data. For a summary the reader is referred to table 5-2.
click to enlarge
Earth reflectance spectra (sun normalised intensity) for various cloud and surface conditions. The inset shows the variation in the reflectance spectrum due to changes in the thermodynamic state of water from liquid water to ice. The large difference in the reflectance spectrum around 1600 nm is used to derive information on the thermodynamical state of water in clouds. (Graphics: IUP-IFE, University of Bremen)
|Parameter ||Spectral Window (nm) ||Retrieval Algorithm ||Retrieval Algorithm Reference |
|CF ||PMD (RGB) ||OCRA HICRUSPCASPICI ||Loyola 1998 Grzegorski et al. 2004 Yan 2005 Krijger et al. 2005 |
| ||reflectance near O2 A-band ||FRESCO SACURA ||Fournier et al. 2006 Kokhanovsky et al. 2005 |
|CTH ||O2 A-band ||FRESCOSACURA ||Fournier et al. 2006 Kokhanovsky et al. 2005, 2006 |
|COT ||reflectance VIS-NIR ||SACURA ||Kokhanovsky et al. 2005, 2006 |
|CGT ||O2 A-band ||SACURA ||Kokhanovsky and Rozanov 2005 |
|Reff,cld ||reflectance VIS-NIR ||SACURA ||Kokhanovsky et al. 2005, 2006 |
|CTP ||reflectance NIR-SWIR ||SACURA ||Kokhanovsky et al. 2005, 2006 Acarreta et al. 2004b |
|AAI ||340 and 380 || ||de Graaf and Stammes 2005 |
|AOT ||several wavelengths in the VIS ||SCIA-BAER ||von Hoyningen-Huene et al. 2003, 2006 |
|Aerosol type ||several wavelengths, combination with AATSR ||SYNAER ||Holzer-Popp et al. 2002a |
Table 5-2: Atmospheric geophysical parameters and retrieval algorithms – nadir cloud and aerosol parameters.